The present invention relates generally to incising tissue and in particular to micro-vitreoretinal surgery blades. In just one example, micro-vitreoretinal (MVR) blades are used to incise tissue for a transvenous chorioretinotomy as treatment for retinal vein occlusion and other indications. Retinal vein occlusions are a common cause of visual loss. Currently, the primary treatments are macular laser (for branch retinal vein occlusion) and pharmacologic agents (for branch and central retinal vein occlusion). These treatments address the side-effects of the retinal vein occlusion, including macular edema and ocular neovascularization. Using these conventional treatments for retinal vein occlusion treatment is typically prolonged (months to years) and expensive.
Recently, a new procedure for treating retinal vein occlusions was reported that involves bypassing the occlusion through surgery to create a chorioretinal anastomosis. Unlike previous attempts to perform this same procedure with laser treatments, “pars plana vitrectomy with multiple transvenous chorioretinotomies (MTC) is safer and more effective. This new method reduces or even eliminates the need for continuing medical therapy; improves or stabilizes visual acuity; and reduces the risk of visual loss.
Currently, there is no ideal tool for performing the critical part of the MTC procedure, which is the transvenous chorioretinotomies themselves. Most modern vitreous surgery is performed with 23 or 25 gauge trocar systems, and the prior art MVR blades typically available for such procedures do not function well in MTCs. The drawbacks of such prior art MVR blades include: (a) the blade tips are too narrow, making it difficult to center the blade on the target vein to achieve complete transection; (b) the side edges of the blades are too dull, causing them to displace rather than transect the target vein; and (c) the blade tips are too long, resulting in increased risk of scleral perforation and globe perforation, particularly in myopic patients with thin sclera.
To circumvent the shortcomings of the smaller caliber blades available with trocar-based microincisional viteoretinal surgical systems, it is generally more effective to create an additional incision in the eye (sclerotomy) to allow use of a larger 20 gauge MVR to perform the MTC part of the procedure. The 20 gauge MVR is not hampered by the drawbacks (a) and (b) above. However, the MTC incision it creates is unnecessarily large and use of the 20 gauge blade requires creation of an additional incision in the eye, which adds steps to the procedure, prolonging the surgery and increases the risk of complications.
Accordingly, there is a need for a new MVR blade that addresses these drawbacks. The inventive blade described herein addresses these drawbacks and provides other related advantages.